1. Field of the Invention
The present invention relates generally to cellular telecommunications. More particularly, the present invention relates to an apparatus and method for the lawful intercept (i.e., "wiretap") of cellular telecommunications data.
2. State of the Art
Lawful intercept of telecommunications between two parties has a long history. Indeed, various techniques for intercepting communications over a fixed wire have been utilized for decades. However, as the field of telecommunications has changed, new techniques have been required for conducting lawful intercept. One new field of telecommunications which has seen explosive growth in the past few years is the field of mobile/cellular telecommunications. In cellular telecommunications, at least one of the parties to the call (which may be a conference call of more than two parties) has a wireless connection to base station system (BSS). Thus, the development of techniques for lawful intercept of cellular communications has been required.
One known technique for the "wiretap" of cellular communications involves the utilization of new equipment which can review the called and calling party telephone number information in proprietary call control logic during call processing, and access a database of telephone numbers in order to determine whether a wiretap is needed. If a determination is made that a wiretap is needed, a conference call is set up between all parties to the telephone call and a third "listening" party. With the conference call as arranged, the third listening party typically does not have the ability to send data to the conference. As will be appreciated by those skilled in the art, the third listening may be a "listening device" or a person.
A second known technique for the "wiretap" of mobile communications is similar to the first technique, except that adjunct equipment is used to upgrade existing equipment which does not have the wiretap capability. When a telephone call is received, the existing equipment compares the called and calling numbers to a database of numbers which are to be tapped, and if the call is to be tapped, the call is forwarded to the adjunct equipment. The adjunct equipment is then arranged to implement a conference call between the parties to the telephone call and third "listening" party.
It should be appreciated that the prior art techniques of wiretapping cellular communications provide useful capabilities. However, the prior art techniques also suffer from certain inadequacies. For example, the technique utilizing adjunct equipment suffers from the requirement that the adjunct equipment is being actively switched in and out. Should the adjunct equipment malfunction for any reason, all calls may be affected. On the other hand, the technique which utilizes proprietary call control logic suffers from the fact that the it cannot be easily implemented on existing equipment. Thus, in order to provide the wiretap functionality, in many situations, the existing equipment will have to be replaced at a great expense.